The present disclosure relates to a power semiconductor device having a high level of reliability.
In general, a power semiconductor device has been widely used to control a motor or used in various switching devices such as an inverter, or the like.
In detail, the power semiconductor device, a semiconductor device used in a power apparatus, is a core component of the power apparatus optimized for the conversion or controlling of power.
The power semiconductor device has a high blocking voltage, a high current, and a high frequency as compared to a general semiconductor device.
As representative power semiconductor devices, there are provided a metal oxide semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), and the like.
Such an IGBT and MOSFET basically have an n-p-n junction structure. That is, since n-p-n junctions are formed between two diodes so that rectification directions are opposite to each other, current does not flow.
However, when a positive (+) voltage is applied to a gate insulated from a p-type semiconductor region using oxides, electrons present in the p-type semiconductor regions are attracted, such that a conductive channel is formed in a portion at which the p-type semiconductor region and the oxides contact each other.
Current may flow between an emitter and a collector or a source and a drain.
Particularly, the IGBT means a transistor manufactured so as to have bipolarity by forming a gate using a metal oxide semiconductor (MOS) and forming a p-type collector layer on a rear surface thereof.
More specifically, an operational principle of the IGBT will be described. When a voltage higher than a threshold voltage of the IGBT device is applied to a gate electrode, a polarity of a surface of a p-type body region positioned at a lower end of the gate electrode is inversed, and accordingly an n-type channel is formed, such that a current may flow between an anode and a cathode.
An electron current injected into a drift region though the channel induces injection of a hole current from a high-concentration p-type collector layer positioned below the IGBT device, similar to a base current of the bipolar transistor.
Due to injection of these minority carriers at a high concentration, a conductivity modulation in which conductivity in the drift region is increased several ten or several hundred times occurs.
Unlike MOSFETs, in case of IGBTs, a resistance component in the drift region may be significantly reduced in size due to the conductivity modulation. Therefore, the IGBT may be used with very high voltages.
Since IGBTs have characteristics such as a low forward loss and rapid switching speeds, the application of IGBTs to fields that may to which existing thyristors, bipolar transistors, MOSFETs, and the like, has increased.
Generally, a power semiconductor device is composed of hundreds of thousands to millions of cells in a single device.
In such a power semiconductor device, since in the case in which latch-up or a short-circuit occurs in a single cell, there is no structure insulating adjacent cells from each other, the entire device is broken.
In the case in which the above-mentioned latch-up or short-circuit occurs, a high degree of heat may be generated in a portion corresponding to a junction of the device.
In an extreme case, a temperature of the corresponding portion is increased to 1400° C. or more due to heat generated at the junction.
Since a melting point of silicon (Si) is 1414° C., the corresponding portion of the device may be completely broken, such that the entire device may be unusable.
Therefore, a technology of cutting off a cell in which a problem occurs before the device becomes unusable due to breakage of the corresponding cell caused by latch-up or a short-circuit in the cell has been required.
A semiconductor apparatus has been disclosed in the following Related Art Document (Patent Document 1).
A semiconductor apparatus having a high breakdown voltage has been disclosed in Patent Document 1.
In detail, the semiconductor apparatus disclosed in Patent Document 1 is characterized in that carrier density may be increased in the vicinity of an emitter and a high breakdown voltage may be obtained by disposing an insulation layer between gate trenches arranged at a predetermined pitch.
However, in the semiconductor apparatus disclosed in Patent Document 1, a region having electrical insulation properties is formed in advance, which is different from the present disclosure in that a device protection layer of the present disclosure may be a region capable of being electrically conducted before a high level of heat is generated due to latch-up or a short-circuit.